A section of the Interstate 80 highway in Morris County, New Jersey was closed to eastbound traffic after a sinkhole opened beneath it on Thursday 26 December 2024. The sinkhole, which was about 12 m across and about 12 m deep appeared close to the town of Wharton, and was first spotted at about 7.40 am local time. Engineers have excavated around the area and then backfilled the whole area with rock and concrete, and expect the highway to reopen on Monday 30 December.
Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.
On this occasion the sinkhole is thought to have been caused by the collapse of an abandoned mineshaft beneath the highway. Morris County was once home to a hundred mine, principally targeting iron ore, many of which dated back to the eighteenth century, and therefore were poorly mapped by modern standards. The last of these mines closed in 1986, but abandoned mines still occasionally cause problems, including sinkholes, in the area. The Mount Pleasant Mine, which opened in 1786 and closed in 1896 is thought to have run beneath the modern Interstate 80 highway. The mine comprised a single inclined tunnel, which averaged 2 m in width and reached over a kilometre in length and more than 424 m beneath the surface.
See also...
